The present invention relates generally to the field of surgical biopsy instruments and methods. More specifically, it relates to a device and method for electrosurgically accessing a pathologically suspect tissue mass in a patient""s body, so as to facilitate the taking of a biopsy sample of the tissue mass, and to facilitate subsequent surgical procedures in the region of the tissue mass.
In diagnosing and treating certain medical conditions, such as potentially cancerous tumors, it may be desirable to perform a biopsy, in which a specimen of the suspicious tissue is removed for pathological examination and analysis. In many instances, the suspicious tissue is located in a subcutaneous site, such as inside a human breast. To minimize surgical intrusion into patient""s body, it is desirable to be able to insert a small instrument into the body for extracting the biopsy specimen.
After removing the tissue samples, additional procedures may be performed at the biopsy site. For example, it may be necessary to cauterize or otherwise treat the resulting cavity to stop bleeding and reduce the risk of infection or other complications. Also, it may be advantageous to mark the site for future surgical procedures should pathological tests performed on the biopsy specimen indicate surgical removal or other treatment of the suspected tissue mass from which the specimen was removed. Such marking can be performed, for example, by the apparatus and method disclosed and claimed in co-pending U.S. patent application Ser. No. 09/343,975, filed Jun. 30, 1999, entitled xe2x80x9cBiopsy Site Marker and Process and Apparatus for Applying It,xe2x80x9d which is hereby incorporated by reference in its entirety.
Electrosurgical techniques have been used in a variety of circumstances, including certain types of biopsy procedures. In electrosurgery, high frequency electrical energy is applied through a primary electrode to patient tissue. The electrical energy flows through the tissue to a return electrode that is in contact with the patent""s tissue. Typically, the return electrode is attached to the patient at a point remote from where the primary electrode contacts the tissue. The tissue adjacent the primary electrode is ablated, to form an opening in the tissue. An electrosurgical biopsy instrument is disclosed and claimed in U.S. patent application Ser. No. 09/159,467 for xe2x80x9cElectrosurgical Biopsy Device and Method,xe2x80x9d assigned to the assignee of the subject application, and which is hereby incorporated by reference in its entirety.
Existing electrosurgical devices have an outer cannula with an elongated hollow outer tube through which a stylet may be inserted and then removed. The stylet is designed so that, when the stylet is fully inserted through the cannula, the distal end of the stylet and electrode disposed thereon, extends beyond the distal end of the cannula. When the stylet is fully inserted through the cannula, the electrode is exposed beyond the end of the cannula. When electrically activated, the electrode ablates the tissue adjacent the electrode, to produce a tissue opening slightly larger than the width of the primary electrode itself. As the primary electrode ablates the tissue, the operator can insert the stylet and the surrounding cannula into the tissue opening until the cannula is inserted to the desired point. However, the width of the electrode has been limited by the inner diameter of the cannula through which it is inserted. Consequently, the tissue opening created by the primary electrode may be smaller than the cannula. What has been needed is a stylet having an electrode that can be inserted through the inside diameter of a cannula yet ablate a passage in tissue large enough for the cannula to easily pass through.
The present invention is directed to a system, specifically a biopsy system, which gives ready access to a desired site or subcutaneous target tissue site within a patient""s body. In one embodiment, the system includes an electrosurgical stylet having an elongate shaft with a proximal end and a distal end. At the distal end of the elongate shaft is an electrosurgical electrode. The electrosurgical electrode has an expanded deployed configuration which is wider than a maximum outside transverse dimension of the elongate shaft, and a constricted configuration which has a width not greater than an outside transverse dimension of the elongate shaft. Another embodiment of the system includes a cannula having a proximal end, a distal end and an inner lumen extending between and in fluid communication with proximal and distal openings. The electrosurgical stylet can be slidably received inside the inner lumen. The electrode of the stylet may be deflected radially inward toward a longitudinal axis of the elongate shaft so that the electrode has a width which is less than an inside transverse dimension of the inner lumen. In this way, the electrode fits within the inner lumen of the cannula, permitting the stylet to be inserted and removed through the cannula. The stylet can be configured to extend distally relative to the cannula to an extended position with the electrode extending distally beyond the distal opening of the cannula and the stylet disposed within the inner lumen of the cannula. The cannula may also have a longitudinally extending side aperature in fluid communication with the inner lumen and disposed proximally of the distal end of the cannula and distially of the proximal end of the cannula.
The electrode may be formed of two or more electrode portions or a single portion extending from and about the distal end of the elongate shaft of the stylet. An electrical conductor extending the length of the stylet provides electrical contact between the proximal end of the stylet and the electrode. In one embodiment, the electrode has a first and second electrode portions that are resiliently deflectable in an inward radial direction when the electrode is resiliently deformed from the expanded deployed configuration to the contracted configuration. The electrode may form an arcuate cutting element which is disposed distally of the distal end of the elongate shaft and which can lie in a plane which is substantially parallel to a longitudinal axis of the elonagate shaft. In some embodiments, the electrode has a width substantially equal to or greater than one half the circumference of the distal end of the cannula. In this way, the system will easily penetrate tissue behind such an activated electrode which is ablating tissue and creating a hole or passage with a circumference which is substantially equal to or greater than the circumference of the cannula.
In another embodiment of the invention, a hand grip is disposed on the proximal end of the elongate shaft of the stylet, and the proximal end of the cannula is provided with a peripheral flange. The hand grip can include a locking lever having a distal end that releasably engages the flange of the cannula. Thus, the stylet and the cannula can be locked together when the locking lever engages the flange to prevent relative axial movement between the cannula and the stylet. When it is desired to remove the stylet from the cannula, the locking lever is actuated to disengage its distal end of the locking lever from the flange, thereby allowing removal of the stylet.
In yet another embodiment of a system having features of the invention, a guide tube is configured to be slidably disposed in the inner lumen of the cannula. A central bore can extend along almost the entire length of the guide tube, except that near the distal end of the guide tube, the bore curves to communicate with a guide tube side orifice in the side of the guide tube. Alternatively, the bore may extend the entire length of the guide tube, terminating in an orifice at the distal end of the guide tube. The guide tube is dimensioned so that, when it is fully inserted into the cannula, the guide tube side orifice coincides with the longitudinally extending side aperture of the cannula.
The guide tube bore is internally dimensioned to permit the passage through it of an electrocautery device that may be inserted through the bore of the guide tube to cauterize the biopsy cavity, following the taking of a biopsy sample or other suitable procedure. Similarly, a marker insertion device may also be inserted through the central bore of the guide tube to insert temporary or permanent markers into a biopsy cavity or any other desired site within a patient""s body.
In accordance with a biopsy procedure of the present invention, the electrosurgical stylet with the cannula surrounding it is inserted into tissue of a patient, using electrosurgical techniques, until the side aperture of the cannula is disposed adjacent a desired site within the patient or a targeted tissue site. The electrosurgical stylet is then withdrawn from the cannula while leaving the cannula in place in the patient""s tissue. A biopsy device can then be inserted through the inner lumen of the cannula to obtain one or more samples of tissue from the targeted site. Alternatively, any desired amount of tissue could be removed so as to complete any necessary surgical intervention, such as removal of a tumor or the like. After the samples have been taken, the biopsy device is removed, again leaving the cannula in place. The guide tube may then be placed into the cannula so that the guide tube orifice coincides with or is disposed adjacent to the longitudinally extending side aperture of the cannula. A cauterization instrument, such as an electrocautery device, may be inserted through the central bore of the guide tube, and activated to cauterize the biopsy cavity. Finally, a marker installation device may be inserted through the guide tube to insert temporary and/or permanent markers at the biopsy site to identify the location from which the biopsy samples were taken. This enables a physician to easily locate the surgical site within the patient subsequent to the procedure if further intervention becomes necessary or for any other reason that it may be necessary to identify the surgical site.
In an alternative embodiment of the invention, a cannula is used that is substantially shorter than the stylet and lacks a side aperture. The system is advanced into the patient""s tissue with the stylet inserted into the cannula and with a tubular spacer element disposed on the proximal end of the cannula. The cannula and the stylet are advanced into the body of the patient to a desired site therein. When the stylet is withdrawn, leaving the cannula in place, a biopsy device can be inserted through the tubular spacer element and the stylet. The spacer element is then removed, and the cannula is moved proximally along the biopsy device to expose the target tissue site to the tissue sampling or other active portion of the biopsy device.